Oncol Park is a private protected wildlife area created by ARAUCO in 1989, comprised of 1,863 acres. This beautiful area extends over part of the Coastal Mountain Range, between the Pacific Ocean and the Río Cruces Nature Reserve.

Oncol hill is the highest peak of the Coastal Mountain Range, at 715 meters above sea level (masl). It is located only 5 kms from the coast, between Nahuelbuta and Mirador hill in the Pelada Mountain Range. This is very significant, because the highest locations of the Coastal Mountains were not affected by the glaciations; the forests found refuge here while the central valley and the Andes Mountains were covered with ice.

Parque Oncol’s distinctive feature is that it harbors the virgin exuberance of the Valdivian forest, which is a mixed and evergreen rainforest. It has the characteristics of a tropical forest, yet located in a temperate region. Similar forests can also be found in New Zealand, but are non existant in the northern hemisphere.

Oncol hill is home to a unique ecosystem, the valdivian forest of the Coastal Mountain Range, also known as the valdivian coastal forest, or the valdivian rainforest. The Coastal Mountains are rich in biodiversity, with a large number of flora and fauna species, many of which are endemic, meaning they can only be found in the valdivian rainforest. Research conducted in this forest indicate that this area contains high levels of biodiversity. For example, over 28 fern species and 9 amphibian species can be found in this ecosystem.